Re: [PATCH 08/14] iomap: Support THPs in readahead

Christoph Hellwig
2020-10-15T09:52:32Z

On Wed, Oct 14, 2020 at 04:03:51AM +0100, Matthew Wilcox (Oracle) wrote:
> +/*
> + * Estimate the number of vectors we need based on the current page size;
> + * if we're wrong we'll end up doing an overly large allocation or needing
> + * to do a second allocation, neither of which is a big deal.
> + */
> +static unsigned int iomap_nr_vecs(struct page *page, loff_t length)
> +{
> + return (length + thp_size(page) - 1) >> page_shift(page);
> +}

This doesn't seem iomap specific, and would seems useful also for e.g.
direct I/O.